The UK economy would be 3.6% smaller by 2040 if net migration fell to zero, forcing the government to raise taxes to combat a much bigger budget deficit, a thinktank has predicted. In this scenario the UK population would stop growing at about 70 million in 2030. The latest official figures showed the UK population was 69.3 million in 2024. Caswell said that unless the fertility rate picked up, then zero net migration “would not be fiscally sustainable for the UK unless there were significant tax rises, and significant tax rises could potentially choke off economic growth”. The forecast came after a sharp fall in net migration in 2025, from 649,000 to 204,000 in the year to June, after a tightening of work visa requirements by the Conservative government.

Source: The Guardian February 04, 2026 11:26 UTC